SOUVENIR COMMITTEE - Birbal Sahni Institute of Palaeobotany

Training Programme on “PALYNOLOGY IN FOSSIL FUEL EXPLORATION”
[ September 10-17, 2012 ]
APPLICATION OF PALYNOLOGY IN COAL EXPLORATION: CASE
STUDY FROM AN INDIAN GONDWANA COALFIELD
RATAN KAR
Birbal Sahni Institute of Palaeobotany, 53, University Road, Lucknow 226 007
E-mail: ratankar@yahoo.com
Gondwana Basins of India occur along several well defined rectilinear belts marking zones of
structural weaknesses. These basins are intracratonic in nature and characterised by the presence of faults
on both sides, known as the boundary faults. These linear depressions became ideal sites for the
deposition of sediments. A characteristic feature of sedimentation in these depressions was the
concomitant sinking of the basin floor, which resulted in the deposition of thick piles of sedimentary
sequences. From the economic point of view, the Gondwana Basins are extremely significant as 99% of
India’s coal reserves are present within these basins.
The initiation of sedimentation in Peninsular Gondwana Basins of India breaks a long gap of nondeposition
in this region, since Cambrian to Late Carboniferous/Early Permian. The sedimentation was
initiated by the deposition of glacigene sediments of Talchir Formation on an uneven Precambrian
basement. After the recession of glaciers, a prolonged sequence of continental fluvio-lacustrine sediments
was deposited. The first phase of fluvial sedimentation is represented by the Karharbari Formation,
comprising poorly sorted coarse-grained sediments, the tectonic set-up being too unstable for the
accumulation of coal seams. Thereafter, conditions became stable and thick piles of coarse to mediumgrained
sandstone, siltstone, shale and coal-seams were deposited comprising the Barakar Formation
(early Permian). The succeeding Barren Measures Formation are composed of coarse to medium-grained
cross-bedded sandstone and iron-stone shales and are devoid of coals. Favourable conditions for coal
formation reappeared again during the deposition of sediments of Raniganj Formation (late Permian). The
post Raniganj sedimentation (Triassic) is characterised by the deposition of varied type of sediments in
different Gondwana Basins, which are completely devoid of coal and comprise mainly of red shales and
pebbly coarse to medium-grained sandstones.
The commercially viable coal seams occur mostly within the Barakar Formation and the
estimation of reserves is done by extensive mapping, followed by drilling operations. In this context,
proper identification of the coal bearing horizons is extremely important for optimizing drilling operations
and for the correct estimation of reserves. As lithological demarcation of the different formations is often
difficult and deceptive, palynology has proved to be an effective tool for the resolution of coal bearing
strata. Palynological assemblages have been of immense use in determining the age, lateral extension and
correlation of the surface and sub-surface coal bearing horizons.
Birbal Sahni Institute of Palaeobotany, Lucknow
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